In the Garden:New England
July, 2011
Regional Report

New flower buds are forming below the open blossoms of these Shasta daisies. When the top flowers fade, I'll cut back to these lower buds. If you look carefully, you can see even newer flower buds forming below those that are getting ready to bloom.

Be a Deadheader

Rain, rain, and more rain! That's been the weather pattern here this spring and early summer. That, along with temperatures on the cool side, have left many vegetable gardens lagging behind where they usually are by this point in the season.

My perennial gardens, on the other hand, are reveling in the regular rainfall and don't mind that the heat is less intense. The plants are lush and beautiful -- even the weeds look good! When I'm out in the gardens pulling those weeds, I'm also checking out the plants that are in need of deadheading. This rather ominous sounding term simply means cutting back the flowers that have passed their prime. In some cases, removing the fading flowers before they set seed will keep the plant producing more new flowers or encourage a second flush of bloom later in the season. In other cases, removing the flowers won't result in more blooms, but will keep the plant looking tidier for the rest of the season. And then there are the plants that, like Pinky and the Brain, are set on taking over the world -- with self-sown seedlings. Deadheading the flowers on these plants keeps the garden from being overrun by invading hordes.

Where and when to snip depends on the growth habit of the plants. Here are some general guidelines to help you decide how to wield your pruners to keep your perennial gardens looking good.

Cut Back to a Lateral Flower, Leaf, or Bud
Lots of popular perennials fall into this category, including Shasta daisies, purple coneflower, peony, veronica, and garden phlox. These are plants that keep producing new flowers over a period of time. With these, cut back the terminal flower or flower head to the next lateral flower or flower bud or, if neither are visible, the next lower leaf. Some plants, like phlox, keep a stemful of strong foliage below where the flowers have faded and these stems should be left in place until the end of the season. On others, like meadow sage (Salvia nemerosa), the foliage gets ratty looking along with the faded flowers and a new clump of basal foliage forms as the first flush of flowers begins to wane. On these, as soon as no new lateral flowers form on the flower stalks, cut the entire stalk back to that clump of foliage at the bottom.

For example, I have several big clumps of Shasta daisies (Leucanthemum x superbum 'Becky') that have just started blooming. When these first flowers begin to fade, I'll cut back the stem about 4 inches to the second set of leaves where I can usually see a new flower bud beginning to form in the axil where the leaf attaches to the stem. But eventually I'll see no new flower buds forming lower on the stem when I trim the faded blooms. Because the foliage stays vigorous, I leave these stems that have finished flowering to grow for the remainder of the season. But by the time frost approaches, new leaves have formed at the base of the plant, so I cut the stalks all the way down to this foliage cluster at this point.

Snip Carefully When New Buds Are Adjacent to Old Flowers
Some flowers don't make deadheading easy. These are generally ones that have a spike or spire of blossoms that don't all open at once. Peachleaf bellflower (Campanula persicifolia) and balloon flower (Platycodon grandiflorus) are examples. To remove the faded flowers, you need to snip out the individual spent blossoms carefully so as not to injure or remove the flower buds still to come that are right next to the spent flowers on the stalk. Once all the flowers on the stalk have finished, then you can cut it down at its base. Because the faded balloon flowers are large and noticeable, I usually take the time to remove them one by one. But I don't have enough hours in the gardening day to spend the time snipping out the faded bellflowers with nail scissors, so I usually tolerate a mix of new and spent flowers until the stalk is mostly finished, then I cut the entire stalk down.

Cut Back Single Flower Stems to the Ground
The flowers of some plants such as heuchera, hosta, pulmonaria, and lady's mantle are borne on a single flower stem that is bare (or mostly bare) of foliage. When these blossoms are finished, cut back the entire stem to its base.

Shear Back the Entire Plant
Many mat-forming spring blooming plants, such as perennial candytuft (Iberis sempervirens), moss phlox (Phlox subulata), and maiden pinks (Dianthus deltoides) can be sheared back by a third or half after they finish flowering. This will keep them from looking straggly, will promote some dense new growth, and may even promote a second flush of flowers later in the season. The same technique also works well for early summer bloomers like catmint (Nepeta spp.) and threadleaf coreopsis (Coreopsis verticillata).

Watch Out for the Self-Sowers
There is always more to do in the garden than time to do it. So if you must skimp on deadheading, listen to the voice of (my) experience and make sure to always deadhead those that self-sow in excess. I grow the lovely looking meadow sage Salvia nemerosa 'Caradonna'. But if I don't deadhead on time, I pay for it in succeeding seasons when my garden is overrun with seedlings that quickly send down a taproot, making it impossible to get them out of the ground without the help of a dandelion digger. The cottage garden charm of mallow (Malva alcea 'Fastigeata') is not enough to spare it in my book. This one really does have designs on world dominion, along with a deep taproot. I can't always keep up with the deadheading, so I have attempted to eradicate it. But volunteers continue to pop up every year, showing me who's really in control out there in the garden!